Veins are thin-walled and contain one-way valves that control blood flow. Normally, the valves open to allow blood to flow into the deeper veins and close to prevent back-flow into the superficial veins. When the valves are malfunctioning or only partially functioning, however, they no longer prevent the back-flow of blood into the superficial veins. As a result, venous pressure builds at the site of the faulty valves. Because the veins are thin walled and not able to withstand the increased pressure, they become what are known as varicose veins which are veins that are dilated, tortuous or engorged.
In particular, varicose veins of the lower extremities is one of the most common medical conditions of the adult population. It is estimated that varicose veins affect approximately 25% of adult females and 10% of males. Symptoms include discomfort, aching of the legs, itching, cosmetic deformities, and swelling. If left untreated, varicose veins may cause medical complications such as bleeding, phlebitis, ulcerations, thrombi and lipodermatosclerosis.
Traditional treatments for varicosities include both temporary and permanent techniques. Temporary treatments involve use of compression stockings and elevation of the diseased extremities. While providing temporary relief of symptoms, these techniques do not correct the underlying cause, that is the faulty valves. Permanent treatments include surgical excision of the diseased segments, ambulatory phlebectomy, and occlusion of the vein through chemical or thermal means.
Surgical excision requires general anesthesia and a long recovery period. Even with its high clinical success rate, surgical excision is rapidly becoming an outmoded technique due to the high costs of treatment and complication risks from surgery. Ambulatory phlebectomy involves avulsion of the varicose vein segment using multiple stab incisions through the skin. The procedure is done on an outpatient basis, but is still relatively expensive due to the length of time required to perform the procedure.
Chemical occlusion, also known as sclerotherapy, is an in-office procedure involving the injection of an irritant chemical into the vein. The chemical acts upon the inner lining of the vein walls causing them to occlude and block blood flow. Although a popular treatment option, complications can be severe including skin ulceration, anaphylactic reactions and permanent skin staining. Another disadvantage is that treatment is limited to veins of a particular size range. In addition, there is a relatively high recurrence rate due to vessel recanalization.
Endovascular thermal energy therapy is a relatively new treatment technique for venous reflux diseases. With this technique, thermal energy in the form of laser or radio frequency (RF) energy is delivered by an energy delivery device that is percutaneously inserted into the diseased vein prior to energy delivery. In a laser therapy, an optical fiber is used as the energy delivery device whereas in an RF therapy, RF electrodes are used as the energy delivery device. The procedure for the thermal energy therapy involves inserting an introducer catheter or sheath and advancing it to within a few centimeters of the sapheno-femoral junction of the greater saphenous vein. In the case of laser therapy, once the introducer catheter is properly positioned, a flexible optical fiber is inserted into the lumen of the catheter or sheath and advanced until the distal fiber tip is near the catheter tip but still protected within the catheter lumen.
Once the catheter and flexible optical fiber are positioned within the vein, the tissue immediately surrounding the diseased vessel segment is subjected to numerous needle punctures to make percutaneous injections of a tumescent anesthetic agent. The injections, typically lidocaine with or without epinephrine, are administered under ultrasonic guidance along the entire length of the greater saphenous vein into the perivenous space. The tumescent injections perform several functions. First, the anesthetic injection inhibits pain caused from the application of energy to the vein. Second, the injection causes the vein to spasm which reduces the diameter of the vein and brings the vessel wall in close proximity to the catheter and the optical fiber. The constricted vessel diameter facilitates efficient energy transmission to the vessel wall through the optical fiber when the laser energy is applied. Third, the tumescent injection also provides a barrier between the vessel and the adjacent tissue and nerve structures, which restricts the heat damage to only the vessel itself and prevents non-target tissue damage.
After the anesthetic injections are made through multiple puncture sites, the catheter is withdrawn approximately 1–3 centimeters while the optical fiber is held steady to expose the distal tip of the optical fiber. A laser generator is then activated to cause laser energy to be emitted from the bare flat tip of the fiber into the constricted vessel. The thermal energy from the laser contacts the blood causing hot bubbles of gas to be created. The gas bubbles transfer thermal energy to the vein wall, causing cell necrosis and eventual vein collapse. With the laser generator turned on, the fiber and catheter are slowly withdrawn as a single unit until the entire diseased segment of the vessel has been treated. The damaged vessel becomes occluded, collapses and can no longer support blood flow.
For such endovascular laser treatment, the injection of tumescent anesthesia through multiple punctures along the diseased segment is considered a standard and necessary step in the treatment protocol. However, there are several disadvantages associated with such a conventional method of administering local anesthesia injections. The anesthetic injection process is cumbersome and is the most time-consuming step in the treatment procedure because of the number of punctures that has to be made. Typically, injections are administered along the entire length of the greater saphenous vein in 2–3 cm increments. The total injection length varies but is usually between 30 and 40 cm.
Accordingly, approximately 10 to 20 injections, and therefore 10 to 20 punctures, are required before the laser treatment can begin.
In addition to the time required to administer multiple injections, peri-venous injections are disadvantageous because they are painful to the patient, leave puncture wounds, and may increase bruising and post-procedure complications because of the way the injection is administered. Each injection is administered under ultrasound guidance due to the necessity of accurately positioning the needle between the fascia and vein. The physician will often use the catheter as a target when inserting the needle into the patient's tissue. In some cases, a physician may inadvertently puncture the vein and even the catheter wall when positioning the needle. When this occurs, the vein wall may be lacerated resulting in excessive bruising and patient discomfort. Lacerations of the vein wall may also result in non-targeted thermal damage outside of the vessel as the gas bubble created by the laser may escape through the laceration into the adjoining tissue and nerve structures. Another disadvantage is that needle punctures that penetrate the catheter wall may damage the integrity of the catheter and/or the optical fiber. Finally, multiple injections require the use of multiple needles and other accessories such as gauze pads and syringes. The medical staff performing the procedure is thus at an increased risk of accidental needle sticks and the potential health hazards associated with unintentional exposure to contaminated blood and other body fluids.
Therefore, it is desirable to provide an improved device and method which delivers vaso-spasming and anesthetic fluids and other procedural drugs quickly, completely and uniformly without multiple injections or multiple needle sticks. It is also desirable that the device and method prevent thermal damage to non-targeted adjacent tissues and nerve structures without requiring peri-venous injections along the entire length of the vein. Further, it is desirable provide such a method and device that reduce patient discomfort associated with needle sticks, decrease procedure time, and minimize postprocedure complications caused by multiple punctures.